Overload protective device.



w. E. DATE.

OVERLOAD PROTECTIVEDEVICE.

APPLICATION mm 02c. 18. 1913.

1,136,657, l Patented Apr. 20, 1915.

UNITED STATES PATENT OFFICE, WILLIAM E, DATE, or wnsrrmnn, nnw'mnsn AssIeNon r0 rim curries-Hardin MFG. oo., or MILWAUKEE, Wisconsin, A coarom'non OF WISCONSIN.

, ovnnnoan rao'rncrrvn nnvxcn.

Patented Apr, 20, 1915.

To all whomz't may concern: Be it known that I, WiLLIAM E. Darn, a citizen of the United States, residing at VVestfield, in the county of Union and State of New Jersey, have invented'new and useful Improvements in Overload Protective Devices, of which the following is a full, clear, concise, and exact'description, reference bein had to the accompanying draw-. ing, forming a part of this specification.

My "inventionrelates to overload protective devices for electric circuits and particularly electric motor circuits.

As is well'understood, it is usual to allow an electric motor more'current for starting is provided with an overload device. set to protect the same in running, such device would be tripped in starting at a permissible current but for some preventive means.

- Various means have been proposed for this purpose, and while the same have fulfilled their function theyhave been found to be 0 en to various objections including comp icity of construction, etc.

This invention has among its objects to provide improved meansfor accomplishing the aforesaid and other results.

The more specific objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates an --embodiment of the invention applied to an alternate current motor. It should be understood, however, that certain features of the invention are applicable as well to'direct current circuits and that various modificationsmay be made in the controller illustrated without departingvfrom the scope of the appended claims.

Referring more specifically tothe drawing, the same shows a single phase motor 1, an electro-responsive control switch 2 therefor and an overload switch 3 controlling said switch 2. The winding 2 of the tions and is adjusted to respond at a cur-- rent value below that permissible in starting.-

Referring now to the additional means shown, the same functions to divert from g Specification of letters Patent. Application filed December 18, 1918. v Serial No. 807,454.

the overload winding in starting,,enoi1gh of. the motor current to render said winding imresponsive to the desired starting current but responsive to an excessive starting current and to thereafter automatically subject said winding to such a percentage of:

the motor current asto insure the desired protection in running. -In practice, this means may be embodied in various different forms. As illustrated, it comprises a variable inductance shunt around the over load winding 8, a solenoid 5 of conventional form being employed for producing the vari able inductance. The solenoid 5 hasa 'laminated magnetframe 6 and a laminatedplunger 7. Its winding is connected in parallel with the overloading winding 3", whereby it is deenergized when the motor circuit is .opened. and is energized toraise its plunger verted thereby at its maximum, whereas when the solenoid draws in its core it increases the inductance of said shunt, thereby forcing more of the motor current through said overload winding, The overloadswitch may thus be readily insured against re spending at safe starting current values until the solenoid 5 attracts its plunger to any predetermined extent, and if desired an increased starting period maybe provided for by retarding the attraction of the solenoid plunger by a dash-pot '8 or other suitable I means. On the other-hand, the overload device is available to protect the motor against excessive surges of current in starting.

. As will now be obvious, the operation is as follows: Switch 4; when closed completes circuit from line L by conductor 10 through the winding 2", by conductor 11 through the overload switch 3, by conductor 12 to-line L. This energizes switch 2 which responds and completes the motor circuit from 'hne L by conductor 13 through the overload winding 3 and solenoid winding 5 in par conductor 15 to line L. T e motor is thus started and the solenoid 5 energized to draw up its core against the action of the dashallel, by conductor 14 throu h the motor, by g 3. In" combination, a load'circuit, an overa f 25' loadprotectivedevicetherefor, the winding pot 8. The motor accelerates during the operation of the solenoid andwhen the'sole noid operates to a predetermined degree the overload switch is rendered responsive for running protection. If the overload switch responds, it opens the energizing circuit of the switch2, causing the sameto drop out and disconnect the motor from circuit.

a What I 'claimas new and desire to secure Letters Jlatent .is

: 1. In combination, a load circuit, an overload protectiv'eig device theref or, and auto- .matic 'mea'nsjsubgectin the wmdmg of said overload device th di erent percentages of the current ,ofsaidjcircuit.

2.. combinati jj aload circuit, an overload ,protectiyedevme therefor, the w n ding of saidoverload'tflevice receiving a limited percentageof the-Toad current'upon closure v of. said circuit, and means operatlngupon closure; of said circuit Eto} increase the percentage of ad current received by said g ih I of sald overload device receiving a limite I percentage of the load: current upon closure of saidcircuit,,and means operating upon closureof said circuit to increasethe percentage of load. current received by said varying the effectiveness of said shunt followinlg the closure of said load circuit.

I 6. n combination, a load circuit, an overe load protective device I therefor having a winding connected. in series therewith, a permanent shunt for said winding, and automatic means controlling the effectiveness of said shunt and o crating upon closureof saidload circuit to ecrease the effectiveness thereof.

7. In combination, a load'circuit, an overload protective device therefor having a winding connected mseries therewith, .a

permanent shunt for said winding, and au-,

tomatic means controlling theefi'ectiveness :therewith, and an inductive winding c0n rent load circuit, anoverload protective device therefor having a windin of said shunt and operating upon closure of said load circuit to decrease the effectiveness thereof, said means having a definite time element.

8. In combination, an alternating current load circuit, a protective device therefor having a winding in series therewith and a variable inductance shunt for said winding.

9. In combination, an alternating current load circuit, a' protective device therefor having a winding in series therewith, an in- 7 ductance shunt for said winding, and means for automatically varying the inductance of said shunt, following the closure of said load circuit. a

.10. In combination, an alternating our- 7 rent load circuit, a protective device having a winding in series therewith, an inductance shunt for said winding, and means operating upon completion of said circuit to decrease the inductance of said shunt.

11. In combination, an alternating current load circuit, a protective device having a winding in series therewith, an inductance shunt for said windin and means operating upon completion 0 said circuit to decrease the inductance of saidshunt, said means having a definite time element.

12. In combination, an alternating our rent load circuit, aprotectivedevice therefor having 'a winding in series therewith and an automatic inductance varying device associated with said winding to vary the sensitiveness of said protective device to current variations insaid load circuit for a temporary period following the closure of said circuit.

13. In combination, an alternating current load circuit, an overload protective device therefor having a winding in! series 00 1 nected in parallel with said former w ndingand having a movable core for varying its inductance.

14. In combination, an alternating curin series therewith, and an inductive so enoid connected in parallel with said winding and having a movable plunger and retarding means therefor.

In witnesswhereof, I have hereunto subscribed my name in the presence of two wit-' nesses.

WILLIAM E. DATE.

Witnesses: C. B. Srnvnns,

LAURA E. Smm. 

